Coded track marker light

ABSTRACT

A track marker light is disclosed as having a housing and barrel containing a light source, an optical system for projecting the radiant energy from said light source as a beam along a predetermined course to be traversed by a ship. A unique relatively rotating reticle and optical filter system is mounted in front of said light source and within said optical system to encodingly turn on and off the light beam being projected from said barrel, so as to enable a navigator having decoding knowledge thereof to navigate said ship along a fine line transition zone at the center of said radiant energy beam.

United States Patent [1 1 Dec. 25, 1973 Larrimore 1 CODED TRACK MARKERLIGHT [75] Inventor: Herbert Larrimore, Lynn Haven,

Fla.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Sept. 5, 1972 [21] Appl. No.: 286,375

[52] US. Cl. 340/29 [51] Int. Cl. 608g 3/00 [58] Field of Search 340/25,29

[56] References Cited UNITED STATES PATENTS 2,913,702 11/1959 Fergusonet a1. 340/26 3,311,877 3/1967 Projector et a1 340/29 SWITCH 2,559,4157/1951 Field et a1 340/29 X Primary ExaminerWilliam C. CooperAtt0rneyRichard S. Sciascia et al.

[57] ABSTRACT A track marker light is disclosed as having a housing andbarrel containing a light source, an optical system for projecting theradiant energy from said light source as a beam along a predeterminedcourse to be traversed by a ship. A unique relatively rotating reticleand optical filter system is mounted in front of said light source andwithin said optical system to encodingly turn on and off the light beambeing projected from said barrel, so as to enable a navigator havingdecoding knowledge thereof to navigate said ship along a fine linetransition zone at the center of said radiant energy beam.

15 Claims, 9 Drawing Figures EXTERNAL POWER SUPPLY PATENIED [151: 2 5I975 SHEET 10F 2 PATENTEDDEBZS ms 3 7 7 SHEET 2 CF 2 BATTERY 5 28 I 94u- /|O| 22 8 FIG. 2

VALUES OF x FIG. 8

l3! CANDLEPOWER m BEAM ANGLE D Z 5, 20 D O I l5 5 2 IO LJJ O 2 11 0 5 O-3 -2 o 2 3 RED 44 GREEN DEGREES FROM BEAM CENTER F IG. 7

GREEN RED FIG. 3

CODED TRACK MARKER LIGHT STATEMENT OF GOVERNMENT INTEREST The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

FIELD OF THE INVENTION The present invention relates, in general, tonavigation instruments, and, in particular, it is a track marker lightwhich facilitates the navigation of a ship or other vehicle along adesired course.

DESCRIPTION OF THE PRIOR ART Heretofore, numerous devices have been usedto navigate a vessel or vehicle along a predetermined course. Forexample, radar systems, sonar systems, channel markers, buoy systems,and various and sundry reference marker lights have been employed forsuch purpose. Although suitable for some purposes, in many instanceseach thereof leaves something to be desired. Most thereof have eitherbeen very complex, bulky, and costly, or the navigation referenceaccuracy thereof has been deficient for many practical purposes.Moreover, the operation of most thereof has necessitated that the humannavigators or operators using them be highly trained and highly skilled,in order to take advantage of whatever optimum accuracies they mayprovide.

SUMMARY OF THE INVENTION The subject invention overcomes many of thedisadvantages of the prior art, in that the construction thereof isrelatively simple, it is sufficiently portable to be deployed by oneperson within a short period of time, and ships and other vehicles canbe navigated by people of very little training and skill with a degreeof accuracy that provides safety and many of the other advantagesnecessary for expeditiously navigating a craft along a desired course.For instance, the navigation marker light constituting this inventionprovides a navigation reference that is sufficient for line navigationaccuracy within one yard at a range of 2 miles to be effected.

It is, therefore, an object of this invention to provide an improvedmarker light.

Another object of this invention is to provide an improved method andmeans for facilitating the navigationof a predetermined vehicle along adesired essentially straight line course within predeterminedenvironmental medium.

Still another object of this invention is to provide an improved methodand means for navigating a ship or other marine vehicle along a straightline watercourse that is safe for the passage thereof.

A further object of this invention is to provide a track marker lighthaving improved visibility.

A further object of this invention is to provide a navigation light thatis not readily susceptible to being destroyed or disabled by thermallyinduced fracture.

Still another object of this invention is to provide a track markerlight that may be deployed on a fixed shore mount or on a suitablestabilized platform within an aqueous or other environment.

Another object of this invention is to provide an improved method andmeans for effecting a glide path ref- BRIEF DESCRIPTION OF THE DRAWINGFIG. 1 is an elevational view, partly in cross-section and partly inblock diagram form, of the track marker light constituting thisinvention;

FIG. 2 is a cross-sectional view showing the structural association ofthe rotary reticle and filter assembly of FIG. 1;

FIG. 3 is a symbolic representation of the filter assembly of FIGS. 1and 2;

FIG. 4 is a cross-sectional view of the barrel of FIG. 1 and the rotaryreticle and filter assembly located in proximity therewith;

FIG. 5 is a schematic view of a preferred configuration of the rotaryreticle of FIGS. 1, 2, and 4;

FIG. 6 is a schematic view of another preferred configuration of anotherrotary reticlethat may be incorporated in the devices of FIGS. 1,2, and4;

FIG. 7 is a graphical comparision of the light intensities of theinstant invention and the known best prior art devices; and

FIG. 8 is a chromaticity diagram which depicts the trichromaticcoefficients of the red and green sectors of the filter of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, thesubject track marker light is shown as having an aluminum barrel 11 inwhich is disposed a front lens 12 that is held against a forwardlyfacing shoulder 13 within said barrel 11 by means of an O-ring 14 whichis urged rearwardly by lens nut 15 having threads 16 which are screwedinto forward barrel end threads 17. A set screw 18 is screwed intothreads 19 in barrel 11 in such manner as to contact lens nut 15 and,thus, retain it firmly in its assembled position. Disposed around theouter periphery of barrel 1] is a plurality of cooling fins 21 whichpreferably extend from a location adjacent to the rear end of saidbarrel in a forwardly direction. In this particular instance, only threeof said fins are shown; however, any number thereof may be employed asnecessary to provide proper cooling for the entire barrel. Integrallyconnected to barrel 11 and near the rear end thereof is a flange 22containing a plurality of screw holes 23. At the rear end of said barrelis located internal screw threads 24 in which is screwed a stainlesssteel coupling 25 by means of external screw threads 26 disposed uponthe front end thereof.

Adjacent to the front end of coupling 25 is a shoulder 27 against whicha rotary shutter assembly 28 is mounted by means of screws 29 extendingtherethrough and into threads 31 located in said shoulder 27 of coupling25.

Rotary shutter assembly 28 is an important feature of the subjectinvention. Therefore, it will be discussed more fully in conjunctionwith FIG. 2 subsequently.

The rear end of coupling 25 contains an adapter portion 32 which, inturn, contains external screw threads 33. Also connected to coupling 25at an intermediate location thereon is a flange 34 having a plurality ofheat dissipation passageways 35 extending radially therethrough and intothe bore thereof. External adapter threads 33 are screwed into internalthreads 36 located in the front end of a hollow aluminum cylindricalhousing 37. The forward end of said housing 37 has an aperture 38therethrough extending along the longitudinal axis thereof in alignmentwith the longitudinal axis of the aforesaid barrel 11. A shoulder 39 isdisposed therein in such manner that an aspheric lens 41 may be insertedand held firmly between the front end of said shoulder 39 and the rearend of the aforesaid coupling 25. Cylindrical housing 37 also has fourapertures 42 extending at 90 intervals therearound which act as a lightviewing and heat exit holes or apertures. Another shoulder 43 is locatedrearward of the aforesaid apertures 42 within housing 37 and extendingaround the longitudinal axis thereof in such manner that reflector 44may be held in abutment thereagainst by means of a keeper 45 havingexternal screw threads 46 which are screwed into internal screw threads47 of the rear end of cylindrical housing 37. Of course, theaforementioned reflector 44 is concavely curved in the direction whichwill cause any light energy impacting thereon to be reflected in theforward direction through the aforementioned lens 41 and on out thefront end of said barre] 11.

Connected to the lower side of cylindrical housing 37, as by welding orany other suitable means, is a plate 49 which has a large aperture 51extending therethrough in alignment with upper and lower apertures 42 ofsaid housing 37. Also located within plate 49 are a trio of threadedholes 52 adapted for receiving a like number of threaded studs 53securely therein. Disposed around said studs 53 are a like plurality ofsprings 54 mounted for compression therearound between another plate 55likewise having a plurality of holes 56 through which said studs 53extend. At the lower end of said studs 53 is a like plurality of knurlednuts 57 which facilitate the adjustment of plate 55 along said studs 53in opposition to the urging of springs 54. In alignment with the axis ofthe aforementioned upper and lower apertures 42 of housing 37 is anotheraperture 58 located through said support plate 55, and extending aroundthe periphery thereof is a spherical-like concave surface which acts asa socket 59 in which a ball 60 is mounted for adjustment positioning. Atthe lower extremity of said ball and extending through said hole 58 is astud 61 having screw threads 62 at the lower end thereof. Of course,stud 61 may be attached to ball 60 in any suitable manner, say, bywelding, screw threads, or integral connection. If desired, theaforementioned socket 59 may be built up on the upper surface thereof insuch manner as to have a boss 63 extending around an intermediateportion of the aforementioned ball 60, and in such instance, thecombination of socket 59, ball 60, and boss 63 constitutes an adjustableball-socketjoint 64. Extending from the underside of support plate 55and extending around aperture 58 is a spherically contoured convexextension 65 which, in turn, mates with a compatible spherically concavesurface 66 disposed within the upper end of adjustable knurled nut 67having internal screw threads (not shown) which allow it to be screwedon to the screw threads 62 of the lower end of the aforementioned stud61.

Securely mounted on a flattened surface 71 of ball 59 is another supportplate 72 which acts as a ground for electrical connection 73 to one ofthe lead wires 74 of electrical cable 75. And mounted on the top of saidplate 72 is a lamp socket 76, likewise which contains electricalconnection 77 which is connected to the other electrical lead wire 78 ofsaid electrical cable 75. Within said electrical socket 76, ispreferably disposed an iodine quartz lamp 81 of such geometricalconfiguration that the intense light energy generated thereby whenelectrically energized will travel forwardly through the aforementionedbarrel 11 either directly through lines 41 and lens 12 or indirectlytherethrough after being reflected by the aforementioned reflector 44.

Surrounding the aforementioned lamp 81 and associated components is asuitable waterproof housing 82. In this particular preferred embodimentsaid housing is shown as being assembled by sections held together withappropriate screws 83 and gaskets 84 and 85. Furthermore, it may readilybe seen that the forward section thereof has a large aperture 86 throughwhich the rear end of coupling 25 extends and to which the rearwardplate 22 of said coupling 25 is bolted by means of bolts 87.

In order to provide a waterproof exit for electrical conduit 75, anysuitable connector assembly 88 is connected to the aforementionedhousing 82. Also, connector assembly 88 may be of such design as willallow it to accommodate several electrical conduits, including one whichwill be connected to the driving means of the aforementioned rotaryreticle assembly 28.

Referring now to FIG. 2 and, in part, to the aforementioned FIG. I,rotary shutter assembly 28 is shown in greater detail as having a frame91 disposed in a circular inset 92 disposed within the inside diameterof the front end of coupling 25. Disposed along the axis of barrel 11and within said frame 91 is an aperture 93, and held in place in frontthereof is a filter 94, the lefthand half section 95 of which is greenand the righthand half section 96 of which is red and a center line 97extending vertically therebetween being lapped clear for a width of M2,wherein A is the wavelength of the sodium D-line. Filter 94 ispreferably heat treated to temper it, so as to make it fractureresistant when exposed to high temperatures or when exposed to rapidlychanging temperatures. If heat treatment thereof is employed, it may benecessary to lap the abutting red and green edges twice once before andonce after heat treating, in order to provide an optimum fittherebetween.

A front view of said red and green filter 94 is best seen in FIG. 3. Afront frame 98 is disposed in front of said filter 94 in such manner asto hold filter 94 in place within rear frame 93. As may readily be seen,frame 98 also has an aperture 99 therethrough along the axis of theaforesaid barrel 1], so that light energy from lamp 81 may readily passthrough the entire reticle assembly under certain circumstances.Disposed within the frontal area of frame 98 and covering the aperturethereof is a circular shutter 101, which is mounted for rotation betweena top drive wheel 1.02 and a pair of lowered idler wheels 103 and 104 onbearing screws 105 and 106, respectively, the shutter of which may bestbe seen in FIG. 4. Of course, as may readily be seen, said shutter drivewheels and idler wheels are configured in such manner as to firmly holdrotary shutter 101 in place as it is rotated in front of filter 94. Toeffect rotation thereof, a drive motor 107 is connected by means of ashaft 108 to said shutter drive wheel 102, which is also connected tothe rearward extension of shaft 108 for support within bearing holes 109located within the upper end of rear and front frames 91 and 98. In thisparticular embodiment, drive wheel 102 drives rotary shutter 101 byfriction; however, gear teeth or any other suitable means may beemployed for such purpose, if so desired. Drive motor 108 is, of course,electrically driven and, thus, electrical leads are connected to anysuitable electrical energy source, perhaps through the aforementionedconnector assembly through which electrical conduit 75 passes.

FIGS. 5 and 6 show representative embodiments of circular rotatableshutters 101 and 101'. As seen in the shutter of FIG. 5, it contains aclear section 111 and a spiral-like opaque section 112. Said opaquespiral-like section of course starts adjacent to but not exactly on thecenter 113 of rotary shutter 101 and approaches the periphery thereofwith an ever increasing cross sectional area until such time as itreaches the periphery thereof and extends in an ever decreasing crosssection around it for a predetermined distance.

The aforementioned rotatable circular shutter 101 of HO. 1 is, withoutlimitation, herewith defined as being the preferred embodiment thereofthat is incorporated in the instant invention. In order to morespecifically define the shutter or light-stop aspect thereof, opaquearea 112 is herewith disclosed as being bounded by a portion of thecircular periphery thereof and by a pair of spiral lines conforming tothe following mathematical expressions, respectively:

(p a1) 4ac6,

and

(p a) 8ac0,

where:

p the distance from each of the spiral lines to the center of theshutter;

a the radius of the circle of clear aperture,

c a constant for each line,

the angle around the circular shutter.

The embodiment of shutter 101 shown in FIG. 6 likewise has a clear area115 and an opaque area 116. Opaque area 116 likewise commences adjacentto but not exactly at center 117 of shutter 101' and extends directly tothe periphery thereof. As shown, the upper portion of the opaque section116 is a straight line 118 while the left-hand edge thereof isspiral-like in configuration and extends downwardly and leftwardly in acurve which ultimately reaches the circular periphery thereof.

The points of the opaque sections 112 and 116, respectively disclosed inFIGS. and 6, preferably start at a distance that is one-quarter of thewavelength of the light broadcast by lamp 81 from the shutter centers113 and 117. Hence, as will be more fully discussed below, when saidshutters 101 and 101' are rotated, there is a center portion thereofthat is transparent to light energy for a diametrical dimension of M4.

For the purpose of electrically energizing lamp 81 and electricallydriving motor 107 an extended power supply 121 may be used as indicatedin FIG. 1. Also, in the event it is desired to make the subject trackmarker light selfcontained and portable, electrical power may besupplied to light 81 and motor 107 by means ofa 28 volt battery 122connected thereto through an on-off switch 123.

As a general rule, the type of mounting means employed to secure thesubject instrument at some fixed position is determined by operationalcircumstances. Hence, it would appear to be sufficient to say that theaforesaid housing 82 may be mounted on any suitable support plate 124which, in turn, as previously suggested, may be connected to anyappropriate support means.

The aforementioned generally configured track marker light assembly hasbeen disclosed herein in such manner that it would be well within thepurview of one skilled in the art having the benefit of these teachingsto construct such a light to make it effective for any givenenvironmental and operational situation. Hence, it has only beengenerally disclosed as a new combination of elements which produce newand improved results that implement the objectives previously mentioned.However, without intending to limit the scope thereof, from this pointon said track marker light will be more specifically designed in suchmanner that it will be readily useful in providing a very narrow linefor visual navigation through narrow channels or other obstacles byboats or ships. Accordingly, the particular embodiment which will now bediscussed in greater detail is intended to fulfill both the requirementsof being portable and effective as a buoy mounted light. To fulfill suchrequirements, the weight and overall size of the entire instrument mustbe kept to a minimum. In the case of the buoy mounted light, the lightmust be servo driven for stabilization with a low inertia factor.Specifically speaking, said marker light is intended to be visible at adistance of2 miles with the unaided eye during daylight hours when theatmospheric transmission of light is approximately percent per mile. Ofcourse, in order for said light to be small in size, portable, have along life, and perhaps be battery operated, the operation thereofdictates that a high efficiency must be obtained in the conversion ofelectrical energy to a projected light beam while achieving the desiredrange of visibility.

It would perhpas be noteworthy at this time that, although theaforementioned filter 94 is depicted as having green and redhalf-sections, other combinations of colors such as green, red, blue, oryellow may be used, as long as the chromaticity of the correspondingbeam is within the boundary limits for that color on the lnternationalCommission on Illumination Chromaticity Diagram. Furthermore, thecircular rotary reticle should be so designed that the transition zoneeffectively occurring at the center thereof is sufficiently narrow sothat when it is directed along the center line of a ship or othervehicle being navigated at maximum range from the subject light, thelook-out person on the port side of the bridge thereof will see a greenlight, while the look-out person on the starboard side thereof will seea red light. If, in such case, for instance, the maximum look-outseparation is assumed to be 10 feet, this corresponds to a maximumtransition zone width of 8.33 X 10 4 radians or approximately 4.76 X 102 degrees.

As previously suggested, the subject track marker light should beprovided with sufficient cooling to protect the optical componentsthereof from heat damage and to reduce the safety hazard thereof tohuman personnel located nearby. Moreover, the subject instrument must becooled sufficiently so that it will function satisfactorily in directsunlight. In order to cause such conditions to exist, any suitablecooling system may be combined therewith, or, in the alternative, thehousing and barrels, etc., may also be designed as to have cooling finsor other cooling means attached thereto as is necessary to effectoptimum operation thereof for any given operational circumstances. Sodoing would, of course, obviously fall within the capabilities of theartisan constructing the subject track marker light by means of theteachings disclosed herewith.

Furthermore, it would appear to be noteworthy that since barrel 11 andcylindrical housing 38 are made of aluminum and are separated bystainless steel coupling 32, said coupling 32 would greatly restrict theflow of heat from said cylindrical housing to said barrel. Hence, barrel11 and coupling 32 which effectively contains the lens optical systemare less subject to being fractured by rapid ambient temperaturevariations, as would occur if the track marker light were moved from anatmospheric environment to an underwater environment while beinglighted. In turn, such structural arrangement tends to prevent, or atleast substantially reduce, the probabilities of inaccuracies fromoccurring due to rapid temperature changes.

The selection and design of the lenses incorporated in this inventionare of considerable importance to the optimum operation thereof. Theselection of the projector or objective lens 12 was governed more byphysical size and cost than by basic lens design. Assuming that thesystem is diffraction limited, the resolution limit would be a functionof the projector lens diameter and, thus, a trade-off must be madebetween resolution and physical size. Since the preferred embodimentherewith disclosed has been constructed to hold the diameter of barrel11 to under 3 inches and a total instrument length to less than 2 feet,these size considerations dictated that the objective lens be no largerthan 75mm in diameter, nor that they have a focal length longer thanapproximately 500mm. A standard 60mm by 375mm achromat lens meets theserequirements and is inexpensive. The diffraction limit for such diameterlens is approximately 2.35 are seconds, which corresponds to aresolution limit of 0.134 feet at a maximum range of 2 nautical miles.

Condenser lens 41 must be fast that is, have a small aperture to focallength ratio for efficiency. As shown in FIG. 1, it is near to andsubjected to direct heat from the light of lamp 81 and, thus, must beheat resistant. The use of aspheric lenses, though not easily fabricatedto extreme accuracies, as a general rule hold aberrations to a minimumand are inexpensive when molded. Because aspheric lenses provide fastlenses that are suitable for applications as condenser lenses wheresurface accuracy is not critical, such aspheric lens has been employedas condenser'lens 41 in the preferred embodiment of FIG. 1.Nevertheless,.to illuminate filters 94 evenly, aspheric condenser lens41 must be lapped after molding and must be relatively free of zones.For this purpose, an off-the-shelf pyrex aspheric lens having a focallength of 26mm and a diameter of 43mm with an f/1.6 speed met therequirements of this light and, hence, was incorporated therein ascondenser lens 41. With such lens, the light source 81 should be locatedjust outside the focal plane of the aspheric condenser lens 41, in orderto cause its image to focus just outside of projector lens 12.

The aforementioned reflector 44 is a spherical collector mirror that islocated behind lamp 81, with lamp filaments adjusted so as to bedisposed at the center of curvature thereof. Reflector 44 collects thelight that would otherwise be lost on that side of lamp 81 and reflectsit back along its original path through the lamp to and throughcondenser lens 41. As with aspheric lens 41, a fast mirror is desirablefor efficiency. The limit therefor is f/.25, which would be ahemisphere. However, for this application, a full hemisphere cannot beutilized because all of the light collected by mirror 44 could not betransmitted back to condenser lens 41 unless lens 41 is constructed insuch manner as to be the same size and speed. lfa line is drawn from theedge of condenser lens 41 through the center of the light source thatis, through the center of the light producing filament of lamp 81 to theopposite edge of mirror 44, the light aperture of said mirror isindicated. Therefore, the limiting speed or efficiency of the subjectcollector-condenser arrangement is limited by the speed of condenserlens 41. Optimization of reflector 44 was effected by selecting a frontsurface pyrex that has a 52mm diameter and an 18mm focal length or anf/.35 speed.

In order to produce color coded beams which may be sighted by the humanoperators navigating the ship or other vehicle along its intendedcourse, the aforementioned filters 94 should be located at the focalplane of projector lens 12 and in an aperture near condenser lens 41.Hence, they are disposed as best shown in FIG. 2 but also as partiallyshown in FIG. 1. Due to their location, filters 94 are subjected to heatfrom the radiated beam of light from lamp 81 and as a result ofconduction along the metallic parts associated therewith, which are,likewise, subjected to the heat generated by lamp 81. Of course, theprimary threat of destruction to filters 94 is caused by the aforesaidradiated energy from lamp 81, since the high intensity beam therefrommust be transmitted therethrough. Nevertheless, a lesser threat from theaforementioned conducted heat is also of sufficient threat to the entireinstrument to make it necessary to alleviate it as much as possible, asby using the aforementioned stainless steel heat restricting couplingbetween the collector-condenser housing and the filter holder. Suchconstruction is, of course, desirable because the exposure of filters 94to excessive heat has two detrimental effects, viz., causes fracture.thereof and also causes chromaticity shift to occur therein.

The construction of filter 94 is somewhat critical, in

abutting lapped surfaces of'said red and green sections.

would appear as a white zone at a distance of 2 miles from the subjectinstrument would be no more than 0.006 ft. and would be unresolved, dueto the diffraction limit on resolution at that distance being 0.134feet. Therefore, when crossing the beam from green to red, the humannavigator or outlook of the vehicle being navigated should see green,yellowish-green, yellowish-red, and red in that order, since the whitezone center would mix with either the red or the green or both,depending on the position of the viewer of the beam.

In order to optimize the radiant energy generated by lamp 81, a 75 Q/CLiodine-quartz lamp was selected, as previously indicated. This lam-pis'designed to operate on 28 volts which may be supplied by suitabledirect current battery-122, and, in all probability, has a lifeexpectancy of approximately 2,000 hours at said 28 volts. On the otherhand, in the event a longer life for lamp 81 is required and a reducedoutput is acceptable, the voltage supplied thereto may bereduced.Conversely, where an extremely high output is required and ashort life can be tolerated, lamp 8] of the aforementioned type may beoperated at significantly higher voltages. The visibility requirementfor the entire instrument is met when the lamp is operated at itsaforementioned design voltage of 28 volts; but, of course, itmay beoperated from a variable power source and, thus, dimmed or brightened asnecessary to conserve power or increase the visibility range thereof.-

An important feature of the instant invention is the constructionthereof in such manner that the position of lamp 81 may be adjusted toeffect optimum focus and visibility thereof. To adjust lamp 81 in thevertical direction it is only necessary to make the proper adjustment ofknurled nuts 57 in opposition to the urging of springs 54, and to effectthe proper positioning of the filaments of said lamp 81, knurled nut 67may be loosened and the movement of the lamp within its ballsocket jointeffected until it is properly located at the intersection ofthelongitudinal axis of barrel 1] and the center line between the centersof upper and lower apertures 42 in housing 37 or at any other desiredlocation. Of course, oncepositioned, knurled nut 67 is tightened tothereby cause a firm friction fit to exist between the bottom' surfaceof ball ,60 and the upper surface of spherical socket 59.

Adjustment of the filters should also be made so as to position them atthe principal focus of the projector lens by screwing coupling 25, whichholds the filters and aperture, in or out of barrel 11 as required. Theprincipal focal point may be determined either with an illuminateddiffraction grating and mirror or with a 3 inch or larger callimator. Ifexcessive backward movement is required at the coupling, a spacer (notshown) may be inserted behind projector lens 12, so as to move itforward. For such purpose, set screw 18 is loosened to remove lens nutso that said spacer may be installed and after installation thereof, itis properly tightened to prevent further movement thereof.

In order to insure operability of the instant track marker light and toascertain that new and improved results were effected thereby, aphotometric evaluation was made thereof. For example luminous intensity.

measurements were conducted thereon and compared to similar measurementsmade on the best known other lights of the prior art. The results ofsaid measurements are graphically depicted in FIG. 7 in which candlepower versus beam angle has been represented for each thereof.- In thisfigure, the transition zone is shown as being located at the center ofthe abscissa with green on the right and red on the left thereof.

Referring again to FIG. 7, curve 131 represents the candle power versusbeam angle that is obtained by the subject light. Curves 132 through 135represent the candle power versus beam angle of the aforementionedlights of the prior art. Although it may be noted that at the transitionzone the intensity is approximately the same for the subject inventionand the light represented by curve 132, it should also be noted that theintensity of the subject track marker light is considerablyhigher thanany of the lights of the prior art between the red angles of 0 to 3degrees and between the green angles of 0 to +3 degrees, with 0 degreesconstituting the center of the observed beam. Furthermore, it wouldappear to be noteworthy that the minimum intensity of the instant trackmarker light is approximately 5,000 candellas. This corresponds to avisual range of approximately 3 miles for 0.9S.detection during mid-daywith the sun at its zenith and with the atmospheric transmission beingapproximately percent per mile. Thus, it may readily be seen, that whencomparing curve 131 of the subject invention with curves 132 through 135of the devices of the prior art, that the subject invention is superiorthereto for many given operational purposes.

Again, because the chromaticity of instruments of the type constitutingthe subject invention are extremely important, the spectral energydistribution of the red and green portions of the beam of the subjectlight were measured with a Beckman model DB Spectrophotometer. Theresults of said mesurements are shown in the chromaticity diagram ofFIG. 8, with the trichromatic coefficients of the red sector being X 70and Y 30, and the trichromatic coefficient of the green sector beingX=25 and Y=47. Hence, it may be seen that the trichromatic coefficientsof both the red and green sectors fall within the allowable valuesrepresented by curve 136.

THEORY OF OPTIMUM CONSTRUCTION w= l.22 )t/D where w angular resolution,it wavelength, D diameter of aperture.-

The selected values for the subject track marker light are as follows: 1

' X=5.6 x 10-5 cm,

Substituting these values in equation (1) yields w= 1.22 X 5.6 XlO'5/61.14 X 101 radians or 2.35 arc seconds.

At the maximum range of 2 miles, this angular spread corresponds to 1.14X 5 X l2,000 feet or 0. l 34 feet.

For the purposeof calculating the width of the transition zone, thefollowing definitions will be used:

Q angle of white zone,

a filter polish accuracy in meters,

d focal length of projection lens in meters,

R working range in feet,

X width of white zone at R range in feet. Then the maximum separation ofthe filter elements is 2a, and

2a/D X/R The known values of the subject track marker light are:

a A A at center X 109 meters,

d 0.06 meter, 7

R 12,000 feet.

By substituting these values in equation (2),

X= 2(600 x 10-9 x 1.2 x10 /0.06 x4 0.06 feet.

From the foregoing, it may be seen that if the white transition zonecould be resolved at 2 miles, as a result of the flatness of theabutting edges of the red and green sectors of filter 94 not exceedingone-quarter wavelength, it would not exceed 0.06 feet. Thus, the whitetransition zone would, indeed, be a very fine line which could be usedas a reference for precisely traveling a predetermined course withsafety and in a most expeditious manner.

MODE OF OPERATION The operation of the present invention will now bediscussed briefly in conjunction with all of the figures of the drawing,but primarily in connection with FIGS. 1 and 9.

Referring first to FIG. 9, in the event that it is desired to travelfrom left to right along a straight line course 141 in order to avoidsay submerged objects located within the aqueous area around a port, atrack marker light (TML) 142 like that specifically disclosed in FIG. 1is mounted in a fixed position at some location, either on land or onsome other stabilized platform, in such manner that the light beamtherefrom will be projected along said path or course 141. Assuming thatthe course 141 is the proper path to take for a ship to get into port,as it approaches said port it will come into the path of the projectedbeam, as defined by extremities 143' and 145. Assuming, for example,that the ship being navigated approaches the beam from the right thereofand, hence, sights the red color being projected through the red filterof the track marker light. As the ship travels in the general directionof said track marker light 142, the aforementioned rotary reticle 101(or 101) is being rotated and, thus, the navigator observes the redlight being turned on and off intermittently. But due to the uniqueconfiguration of said rotary reticle 101, the on-off periods thereofvary as the navigated ship travels toward the transition zone. Of

course, as viewed in FIG. 9, if the ship is not approach- 6 ing thetransition zone, the off period will be considerably longer than itwould be if the navigated ship were traveling toward the transitionzone. In this way the navigator can turn his ship toward that coursewhich causes the off duration of the blinking red light to be less andless. So doing causes the ship to be navigated toward the desired course141. As the ship crosses said course 141, a momentary transition fieldof view is observed before encountering a blinking green light. At thistime said ship is turned in such manner that the blinking green lightwill be off for lesser and lesser period of time. As a result of huntingback and forth across said transition zone, eventually the ship will belined up on course 141 to the extent that the transition zone will betraversed as long as he is on course. Should he get off coursemomentarily, the navigator or his observers will observe either thegreen or red light beginning to blink at intervals and for durationswhich are proportional to the extent that he is off course. Dependingupon which one is seen, corrective guidance can be effected.

From the foregoing it may readily be seen that one of the importantfacets of the subject invention is that the track marker light can beprogrammed in such manner that only navigators having knowledge of saidprogram will be able to navigate safely along transition zone course141. In effect, then, the instant track marker light 142 becomes a codedmessage broadcaster which enables any person having the code to decodeit and, therefore, to travel safely along course 142 which, for example,may be threaded through various and sundry obstacles within the water ofa port that would otherwise be dangerous or detrimental to a ship orother marine vehicle attempting to pass therethrough. Such coding, ofcourse, is only possible as a result of the rotation of reticle 101 byits drive motor 107 in combination with green or red fliters 94 and theentire light and optical systems which cause radiant energy to beproperly projected therethrough and for a considerable distance, say, 2miles or so, along a course or path desired to be traveled. For suchcoding purposes. as previously suggested, the rotary reticles of FIGS. 5and 6 are employed. They, of course, are just two of the many possiblecoding configurations that may be employed in the subject track markerlight. Nevertheless, it has been found that the two configurationsthereof shown in FIGS. 5 and 6, respectively, are imminentlysatisfactory for their intended purposes.

From the above, it may be seen that the subject track marker lightconstitutes a new and unique method and means for navigating apredetermined vehicle along a particular course or path and that is doesso in such manner that it constitutes a considerable advancement in theart of navigating a vehicle through an otherwise dangerous ordeleterious environmental medium.

Obviously, other embodiments and modifications of the subject inventionwill readily come to the mind of one skilled in the art having thebenefit of the teachings presented in the foregoing description and thedrawings. It is, therefore, to be understood that this invention is notto be limited thereto and that said modifications and embodiments areintended to be included within the scope of the appended claims.

What is claimed is:

l. A track marker light, comprising in combination:

a barrel having a bore therethrough along the longitudinal axis thereof;

an objective lens removably and adjustably mounted in the bore of saidbarrel in proximity with the front end thereof;

a heat restriction coupling, having an aperture therethrough, removablyand adjustably mounted in the bore of the rear end of'said barrel insuch manner as to extend rearwardly therefrom;

a cylindrical housing, having open front and rear ends, a plurality ofheat-venting apertures through the wall thereof, and a pair of inwardlyextending shoulders respectively located forwardly and rearwardly fromsaid heat-venting apertures, with the open front end of said couplingconnected to the rear end of said coupling;

an aspheric condenser lens effectively disposed between the frontsurface .of the forwardly located one of said inwardly extendingshoulders of said cylindrical'housing and the rear end of said coupling;

a, forwardly facing concave reflector securely mounted within the openrear end of said cylindrical housing and against the rear surface of therearwardly located one of said inwardly extending shoulders thereof;

lamp means effectively connected to said cylindrical housing in suchmanner that the filament portion thereof is located'between saidaspheric condenser lens and said reflector and substantially on arearward extension of the longitudinal axis of the aforesaid barrel, soas to beam light energy therethrough; and

means connected-between said cylindrical housing and said lamp means foradjusting the position thereof in any direction within said cylindricalhousing. s

2. The invention of claim 1, further characterized by means disposedwithin-said heat restriction coupling in alignment with the aperturethereof for color coding the light passing therethrough.

3. The invention of claim I, further characterized by shutter meansdisposedin alignment with the aperture of said heatrestriction couplingfor the timely stopping and passing of radiant energy therethrough.

4. The invention of claim 1, further characterized by a waterproofhousing connected to the rear end of said barrel in such'manner as toprovide'a waterproof environment for said heat restriction coupling,said cylindrical housing, said aspheric condenser lens, said forwardlyfacing concave reflector, said lamp means, and the aforesaid meansconnected between said cylindrical housing and said lamp means foradjusting the position thereof in any direction within said cylindricalhousing.

5. The invention of claim 1, further characterized by means effectivelyconnectedv to said barrel and the track marker light incorporating saidbarrel for the cooling thereof.

6. The invention of claim 1, further characterized by means connected tosaid track marker light for the mounting thereof in a fixed positionwithin a predetermined environmental medium.

7. The invention of claim 1, further characterized by means effectivelyconnected to said lamp means for timely supplying electrical powerthereto.

8. The invention of claim I, further characterized by: v

a battery; and I v a switch connected between the output of said batteryand the input of the aforesaid lamp means for. the turning on and offthereof. 9. The device of claim l,wher.ein said barrel is an aluminumbarrel, wherein said coupling is a stainless steel 14 coupling, and saidcylindrical housing is an aluminum cylindrical housing. a

10. The device of claim 1, wherein said is a 60 mm by 375 mrn achromatlens.

11. The invention of claim 1, wherein said aspheric condenser lensis apyrex aspheric lens having a focal length of 26 mm and a dimater of43mm."

12. The device of claim 1, wherein said lamp means comprises: i

a Q/CLiodine-quartz lamp; and v I a socket effectively connected to saidadjusting meansand releasably connected tothe aforesaid lamp for thesupport thereof in apredetermined spatialdisposition between theaforesaid aspheric coridenserlens and forwardly facing concavereflector. Y j I 13'. The device of claim 1, wherein said meansconnected between said cylindrical housing and said lamp means foradjusting the position thereof in any direction within said cylindricalhousing comprises:

a lamp socket; v a

an upper plate, having a trio of spatially disposed threaded holesdisposed around a central aperture,

connected to the lower portion of said cylindrical housing in 'suchmanner that said central aperture is inalignment with the lower one ofsaid heatventing apertures extending through the wall thereof; f

a trio of threaded studs respectively screwed into the trio of threadedholes of said upper plate and extending downwardly therefrom;

a lower plate having a central aperture and a' trio of holes extendingtherethrough, with the trio of holes objective lens thereof having theaforesaid trio of studs extending therethrough; a trio of adjustableknurled nuts respectively screwed ,on the lower threaded ends of saidtrio of studs;

a concave surface located'within the upper surface'of the aforesaidlower plate andextending around the central-aperture therein; i

- surface, with the upper "flat' 'surface thereof connected to the lowersurface-of the aforesaid socket, andwith the lower'convex surfacethereof disposed in complementary slidable abutment with theconcavesurface in the upper portion of said lower plate; a convex surfaceconnected to the lower side of said lower plate around the centralaperture thereof; another threaded stud connected to the lower end ofthe aforesaid ball and extending through the central aperture of theaforesaid lower plate and its concave and convex surfaces;

another knurled nut, having a concave upper surface in compatibleabutment with the aforesaid convex surface located on the underside ofthe aforesaid lower plate,-screwed on the end of said another a ball,having a flat upper surface -anda'convexlower the periphery thereof andby a pair of spiral lines respectively conforming to the mathematicalexpressions 92 a) =4ac0,

and

(p a) 8ac0,

where p the distance from each of said spiral lines to the center ofsaid rotatable shutter,

a the radius of the circle of clear aperture of said rotatable shutter;

c a predetermined constant for each line, and

0 the angle around the circular shutter.

1. A track marker light, comprising in combination: a barrel having a bore therethrough along the longitudinal axis thereof; an objective lens removably and adjustably mounted in the bore of said barrel in proximity with the front end thereof; a heat restriction coupling, having an aperture therethrough, removably and adjustably mounted in the bore of the rear end of said barrel in such manner as to extend rearwardly therefrom; a cylindrical housing, having open front and rear ends, a plurality of heat-venting apertures through the wall thereof, and a pair of inwardly extending shoulders respectively located forwardly and rearwardly from said heat-venting apertures, with the open front end of said coupling connected to the rear end of said coupling; an aspheric condenser lens effectively disposed between the front surface of the forwardly located one of said inwardly extending shoulders of said cylindrical housing and the rear end of said coupling; a forwardly facing concave reflector securely mounted within the open rear end of said cylindrical housing and against the rear surface of the rearwardly located one of said inwardly extending shoulders thereof; lamp means effectively connected to said cylindrical housing in such manner that the filament portion thereof is located between said aspheric condenser lens and said reflector and substantially on a rearward extension of the longitudinal axis of the aforesaid barrel, so as to beam light energy therethrough; and means connected between said cylindrical housing and said lamp means for adjusting the position thereof in any direction within said cylindrical housing.
 2. The invention of claim 1, further characterized by means disposed within said heat restriction coupling in alignment with the aperture thereof for color coding the light passing therethrough.
 3. The invention of claim 1, further characterized by shutter means disposed in alignment with the aperture of said heat restriction coupling for the timely stopping and passing of radiant energy therethrough.
 4. The invention of claim 1, further characterized by a waterproof housing connected to the rear end of said barrel in such manner as to provide a waterproof environment for said heat restriction coupling, said cylindrical housing, said aspheric condenser lens, said forwardly facing concave reflector, said lamp means, and the aforesaid means connected between said cylindrIcal housing and said lamp means for adjusting the position thereof in any direction within said cylindrical housing.
 5. The invention of claim 1, further characterized by means effectively connected to said barrel and the track marker light incorporating said barrel for the cooling thereof.
 6. The invention of claim 1, further characterized by means connected to said track marker light for the mounting thereof in a fixed position within a predetermined environmental medium.
 7. The invention of claim 1, further characterized by means effectively connected to said lamp means for timely supplying electrical power thereto.
 8. The invention of claim 1, further characterized by: a battery; and a switch connected between the output of said battery and the input of the aforesaid lamp means for the turning on and off thereof.
 9. The device of claim 1,wherein said barrel is an aluminum barrel, wherein said coupling is a stainless steel coupling, and said cylindrical housing is an aluminum cylindrical housing.
 10. The device of claim 1, wherein said objective lens is a 60 mm by 375 mm achromat lens.
 11. The invention of claim 1, wherein said aspheric condenser lens is a pyrex aspheric lens having a focal length of 26 mm and a dimater of 43 mm.
 12. The device of claim 1, wherein said lamp means comprises: a 75 Q/CL iodine-quartz lamp; and a socket effectively connected to said adjusting means and releasably connected to the aforesaid lamp for the support thereof in a predetermined spatial disposition between the aforesaid aspheric condenser lens and forwardly facing concave reflector.
 13. The device of claim 1, wherein said means connected between said cylindrical housing and said lamp means for adjusting the position thereof in any direction within said cylindrical housing comprises: a lamp socket; an upper plate, having a trio of spatially disposed threaded holes disposed around a central aperture, connected to the lower portion of said cylindrical housing in such manner that said central aperture is in alignment with the lower one of said heat-venting apertures extending through the wall thereof; a trio of threaded studs respectively screwed into the trio of threaded holes of said upper plate and extending downwardly therefrom; a lower plate having a central aperture and a trio of holes extending therethrough, with the trio of holes thereof having the aforesaid trio of studs extending therethrough; a trio of adjustable knurled nuts respectively screwed on the lower threaded ends of said trio of studs; a concave surface located within the upper surface of the aforesaid lower plate and extending around the central aperture therein; a ball, having a flat upper surface and a convex lower surface, with the upper flat surface thereof connected to the lower surface of the aforesaid socket, and with the lower convex surface thereof disposed in complementary slidable abutment with the concave surface in the upper portion of said lower plate; a convex surface connected to the lower side of said lower plate around the central aperture thereof; another threaded stud connected to the lower end of the aforesaid ball and extending through the central aperture of the aforesaid lower plate and its concave and convex surfaces; another knurled nut, having a concave upper surface in compatible abutment with the aforesaid convex surface located on the underside of the aforesaid lower plate, screwed on the end of said another threaded stud.
 14. The invention of claim 1, further characterized by: a filter having a green section and a red section separated by a lapped vertical intersection therebetween disposed in said heat restriction coupling in alignment with the aperture thereof; a rotatable shutter having a predetermined opaque spiral section and a clear section complementary therewith mounted for rotation in front of said filter; and means connected to saiD rotay shutter for the rotation thereof at a predetermined number of revolutions per minute in front of said filter or flap shutters.
 15. The device of claim 14, wherein the opaque spiral section of the aforesaid rotatable shutter is defined as being bounded by a predetermined circular portion of the periphery thereof and by a pair of spiral lines respectively conforming to the mathematical expressions (92 - a)2 4ac theta , and ( Rho - a)2 8ac theta , where Rho the distance from each of said spiral lines to the center of said rotatable shutter, a the radius of the circle of clear aperture of said rotatable shutter; c a predetermined constant for each line, and theta the angle around the circular shutter. 